Battery carbon fiber electrode making machine and method

ABSTRACT

A machine and process for making a composite battery electrode with a conductive lead cast ribbon extending along and attached to a portion of a carbon fiber material. A lead ribbon may be continuously cast along a longitudinally elongate strip of carbon fiber material. The ribbon may be cast along an edge or edges of a longitudinally elongate strip of carbon fiber material.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.62/820,580 filed Mar. 19, 2019 which is herein incorporated by referencein its entirety.

TECHNICAL FIELD

A variety of different types of batteries have electrodes of a carbonfiber material connected to a lead conductor. There is a need for a wayto cost effectively mass produce electrodes of a carbon fiber materialattached to a lead conductor.

The present invention relates generally to battery electrodes of acarbon fiber material and more particularly to a machine for and methodof making battery composite electrodes with a carbon fiber materialelectrically connected with a lead conductor.

SUMMARY

In at least some embodiments, a method and machine for casting acomposite lead or lead alloy carbon fiber electrode may includeproviding a continuous flow of liquid lead or lead alloy onto alongitudinally elongate strip of carbon fiber material with the liquidlead or lead alloy forming a ribbon on the fiber material having a widthless than the transverse width of the strip of carbon fiber material. Inat least some implementations, a portion of the strip of carbon fibermaterial may be compressed to inhibit flow of the liquid lead or leadalloy transversely into the carbon fiber material. The strip of carbonfiber material with the ribbon thereon may be severed to provide aplurality of individual electrodes.

In at least some implementations the machine have a rotatable drum withat least one mold cavity extending circumferentially around the drum andconfigured to underlie only a portion of the transverse width of a stripof longitudinally elongate material received in part on the drum, a shoewith at least one orifice opening onto a portion of the strip overlyingthe mold cavity and configured to supply liquid lead or lead alloy tothe mold cavity and a portion of the strip overlying the mold cavity,and the shoe having an inlet and an outlet communicating with theorifice, and a device configured to supply liquid lead or lead alloy tothe inlet in a quantity in excess of that required to provide acontinuous flow through the orifice to progressively fill a portion ofthe mold cavity and engage at least part of the overlying strip as theymove past the orifice with excess lead or lead alloy flowing through theoutlet.

In at least some implementations a rib may extend circumferentiallyaround the drum and underlie the strip to limit the extent of generallyaxial flow of liquid lead or lead alloy onto the strip.

In at least some implementations the orifice may have a first portionextending generally axially across at least part of the mold cavity anda second portion extending across part of the strip and spaced from thefirst portion. In at least some implementations the first portion may beaxially elongate. In at least some implementations the second portionmay be circumferentially elongate.

In at least some implementations the cavity may have a plurality ofcircumferentially spaced apart ribs in the cavity. The ribs may extendgenerally parallel to the axis of rotation of the drum.

In at least some implementations the shoe may have a rib adjacent oneend of the orifice, extending into the cavity and extendingcircumferentially upstream of the orifice relative to the direction ofrotation of the drum. In some implementations the shoe may have a secondrib adjacent the other end of the orifice, extending into the cavity andextending circumferentially upstream of the orifice relative to thedirection of rotation of the drum.

In at least some implementations the shoe may have at least one ribbearing on the strip, spaced from the orifice and compressing the stripbetween the rib and the drum.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description of preferred embodiments and bestmode of a method and machine for making battery electrodes of a carbonfiber material connected to a lead or lead alloy conductor will be setforth with reference to the accompanying drawings in which:

FIG. 1 is a fragmentary plan view of a longitudinally elongate compositestrip of a carbon fiber material with a lead conductor ribbon attachedalong each elongate edge of the strip of carbon fiber material;

FIG. 2 is a fragmentary plan view a longitudinally elongate compositestrip of a carbon fiber material with a lead conductor ribbon attachedalong each elongate edge of the strip with equally spaced apart locatorholes through each lead ribbon;

FIG. 3 is a fragmentary plan view of a longitudinally elongate compositestrip of a carbon fiber material with a lead conductor ribbon attachedalong each elongate edge of the strip with lugs of each lead ribbon;

FIG. 4 is a side view of a machine for casting a lead ribbon attachedalong one or both edges of an elongate strip of carbon fiber material;

FIG. 5 is an end view of the machine of FIG. 4;

FIG. 6 is a semi-schematic perspective view of a device for unwinding aroll of an elongate strip of carbon fiber material and feeding it ontothe drum of the machine of FIG. 4;

FIG. 7 is a semi-schematic side view with portions broken away of thedevice of FIG. 6;

FIG. 8 is a plan view of a portion of a periphery of a casting drum ofthe machine of FIG. 4;

FIG. 9 is an enlarged view of the portion within the circle A of FIG. 8;

FIG. 10 is an enlarged fragmentary sectional view taken on line B-B ofFIG. 9;

FIG. 11 is an enlarged fragmentary sectional view taken on line C-C ofFIG. 9;

FIG. 12 is an enlarged fragmentary sectional view taken on line D-D ofFIG. 9;

FIG. 13 is a front view of a shoe of the machine of FIG. 4;

FIG. 14 is an end view of the shoe of FIG. 13;

FIG. 15 is an enlarged fragmentary sectional view taken on line E-E ofFIG. 13;

FIG. 16 is an enlarged fragmentary top view of the shoe of FIG. 13; and

FIG. 17 is a semi-schematic enlarged fragmentary sectional view of theshoe confronting the drum of the machine of FIG. 4.

DETAILED DESCRIPTION

Referring in more detail to the drawings, FIG. 1 illustrate alongitudinally elongate composite strip 20 of electrically conductivecarbon fiber material 22 with a longitudinally elongate electricallyconductive cast lead or lead alloy ribbon 24 (hereinafter lead ribbon)attached to each longitudinal edge 26 of the carbon fiber material. FIG.2 illustrates the elongate composite strip 20 with locator indiciadesirably in the form of uniformly longitudinally spaced apart holes 28in each lead ribbon. These holes 28 may be formed when casting the leadribbon or after the lead ribbon has been cast to the carbon fibermaterial 22 such as by punching the holes through each lead ribbon. FIG.3 illustrates the elongate composite strip 20 in which each lead ribbon24′ includes equally longitudinally spaced apart lugs 30 which may beformed either when casting the lead ribbons or by stamping, punching,severing or otherwise cutting away portions of each cast ribbon 24 toform the lugs thereof. To form individual electrodes 32 of carbon fibermaterial with a lead ribbon attached along one edge, all forms of theelongate strip may 20 be severed longitudinally as indicated by thebroken line 34 and transversely as indicated by broken lines 36.Alternatively, a composite longitudinally elongate strip may be formedwith a lead ribbon along only one longitudinal edge of a strip of carbonfiber material and severed transversely to form a plurality ofindividual electrodes 32.

Typically, each lead ribbon may have a nominal thickness in the range ofabout 0.030 to 0.080 of an inch and a transverse width in the range ofabout 1.2 to 2.0 inches. The carbon fiber material may have a thicknessin the range of about 0.030 to 0.180 of an inch and for automotivebatteries a transverse width of about 6 to 12 inches and desirably 8 to10 inches if lead ribbons will be attached along both longitudinal edgesand a transverse width in the range of about 3 to 6 inches if a leadribbon will be attached along only one longitudinal edge. For stationarybatteries the carbon fiber material may have a transverse width in therange of about 6 to 12 inches where a lead ribbon is attached along onlyone longitudinally elongate edge. Typically, the carbon fiber materialmay include a variety of electrically conductive carbon or graphitefibers (hereinafter both referred to as carbon fiber material) which maybe several hundred feet in length and sufficiently flexible that theymay be coiled into rolls. Suitable elongate strips of carbon fibermaterial commonly referred to as carbon fiber felt are commerciallyavailable.

A suitable method of making carbon fiber electrodes 32 includes castingliquid lead or a liquid lead alloy into an electrically conductive leadribbon 24 along one or both edges 26 of a longitudinally elongate stripof carbon fiber material 22 to produce a composite strip 20 andthereafter severing the carbon fiber material and attached lead ribbonor ribbons to form a plurality of individual electrodes 32. Depending onthe desired application and downstream processing of the composite strip20, each lead ribbon may have locator holes 28 and/or lugs 30 eithercast therein or subsequently formed by various punching, stamping,cutting, shearing, and/or severing operations which remove portions ofthe cast lead ribbon to form the locator holes in and/or lugs of thecast lead ribbon.

FIGS. 3 and 4 illustrate a machine 40 for continuously casting aconductive lead or lead alloy ribbon 24 attached along one or both edges26 of a longitudinally elongate strip 22 of carbon fiber material. Themachine may include a frame 42 on which a casting drum 44 is journaledfor rotation by a motor 46 which is desirably a variable speed electricmotor drivingly connected with the drum such as by a suitable belt 48 orchain. Portions of a longitudinally elongate strip 22 of a carbon fibermaterial may be received on the drum 44 and the drum may have a cavity50 (FIGS. 8-10) for casting a continuous lead ribbon or ribbons 24respectively attached to one or both longitudinally extending edges ofthe carbon fiber strip of material. As shown in FIGS. 6 and 7, a roll 52of the carbon fiber material may be unwound and disposed on the rotatingdrum 44 by a uncoiling device 54. In operation of the machine 40, liquidlead is supplied through a shoe 56 to a proportion of a cavity(s) 50 tocast and attach a lead ribbon or ribbons 24 along one or bothlongitudinal edge portions of the carbon fiber strip 22 of material.Liquid lead under pressure may be supplied from a lead pot 58 of amelting furnace 60 by a pump 62 through a conduit 64 to an inlet of theshoe 56 with excess liquid lead returned to the lead pot through areturn conduit 66. Typically, the liquid lead may be supplied to theshoe 56 by the pump at a super-atmospheric pressure and a temperature inthe range of about 700 to 1,100 degrees F. On a peripheral portion ofthe drum 50 generally opposite the shoe 56 there may be a series ofthermostatically controlled water spray nozzles 68 for maintaining theouter peripheral surface of the drum at a predetermined desiredtemperature in the range of about 200 to 400 degrees F. The compositestrip 20 of carbon fiber material with a lead ribbon or ribbons attachedthereto is removed from the drum as a longitudinally elongate continuouscomposite strip 20 which may thereafter be severed into individualelectrodes.

For retaining a portion of the carbon fiber strip 22 of material on thedrum 44 while the lead ribbon or ribbons 22 are cast thereon, as shownin FIGS. 8 and 9, a plurality of circumferentially and axially spacedapart spikes 72 are disposed circumferentially continuously aroundperipheral surface 74 of the drum. As shown in FIG. 11, each spike mayproject substantially radially outward of the peripheral surface 74 ofthe drum typically on the order of about 0.04 to 0.06 of an inch and betapered at an included angle typically in the range of 10 to 20 degreesand desirably about 15 degrees relative to its axis to a relativelysharp point at its distal end. In operation of the machine, these spikes72 extend into the strip of carbon fiber so that it does not moverelative to the drum while the lead ribbon or ribbons 22 are castthereon. As shown schematically in FIGS. 6 and 7 the unwinding device 54disposes succeeding portions of the carbon fiber strip 22 onto the drum44 and into engagement with the spikes 72. This unwinding device 54 mayinclude an arbor 76 on which a roll 52 of the strip 22 of carbon fibermaterial may be rotatably received, a guide band 78 for directingportions of the strip as it is unrolled onto the rotating drum, androllers 80 for forcing the strip onto the spikes 72 as it passes betweenthe rollers and the rotating drum. Desirably the rollers 80 extendtransversely across the entire width of the strip and are journaled tofreely rotate in response to rotation of the drum 44 and the advancementof the carbon fiber strip 22 onto the drum. Of course, persons ofordinary skill may readily devise other devices for applying successiveportions for a strip 22 of a carbon fiber material onto the rotatingdrum 44 and into engagement with the spikes 72.

For casting each lead ribbon 24, the drum 44 may have a separate cavity50 recessed in and extending circumferentially continuously around theperipheral surface of the drum. In the drawings only one cavity 50 forcasting one lead ribbon 24 along one longitudinal edge 26 of a carbonfiber strip 22 is shown, and will be described in detail. However, formaking a composite strip 20 with a lead ribbon 24 attached to eachlongitudinal edge 26 of a carbon fiber strip two separate cavities 50may be provided each adjacent to and somewhat underlapping one of thelongitudinal edges 26 of the strip 22 of carbon fiber. The cavityunderlaps and may also overlap an adjacent edge portion 26 of the carbonfiber material and desirably has an axial end provided by acircumferentially continuous rib 82 or raised portion which tends tolimit the generally axial extent to which liquid lead flows into andaround the edge portion 26 of the carbon fiber strip. To at least someextent, the liquid lead penetrates into an edge portion of the carbonfiber material extending into the cavity and when solidified attaches orsecures the lead ribbon to the carbon fiber materials and provides anelectrically conductive path or conductor for the carbon fiber material.In at least some instances the liquid lead may saturate at least part ofthe edge portion of the carbon fiber material.

Desirably to cast a lead ribbon 24 having a sinuous surface with aplurality of circumferentially spaced apart and transversely extendingcogs or grooves, the cavity 50 may have a plurality of circumferentiallyspaced apart and axially extending bars or lands 84 in the cavity anddisposed completely around the cavity. As shown in FIG. 12, each land 84extends generally radially outward of the base of the cavity and mayhave a height or extent less than the depth of the cavity so that theouter face 86 of each land is disposed radially below or inboard of theperipheral surface 74 of the drum. The generally axial outer edge 88 ofthe cavity is desirably axially outboard of the adjacent end of thelands 84. The serrated, sinuous or cogged surface of each lead ribbonensures that when solidified and while the ribbon is still being carriedby the rotating drum 44, it does not move or shift generallycircumferentially with respect to the portion of the strip 22 of carbonfiber on the drum to which it is joined or attached and after removalfrom the drum it may facilitate further downstream processing of theelongate composite strip 20 such as for advancing the strip or webthrough a die for punching locator holes, forming lugs on of the leadribbons, pasting the composite strip, cutting or severing the compositestrip into individual battery electrodes, etc.

In operation of the machine 40, liquid lead is continuously supplied tothe cavity 50 of the rotating drum 44 through the shoe 56. As shown inFIGS. 13 and 14 the shoe 56 has an arcuate outer face 90 forcomplimentary mating engagement with a portion of the periphery of thedrum 44. The shoe 56 may supply liquid lead to each cavity 50 of thedrum with a continuous flow of liquid lead through a separate orifice 92opening through the arcuate face 90 of the shoe. Desirably the orifice92 may have two outlet openings 94 & 96, slightly spaced apart from eachother. The openings 94 and 96 may have a generally rectangularconfiguration and the opening 96 may be elongate and disposedlongitudinally generally parallel to the axis of rotation of the drum.Typically the opening 94 of the orifice through the face 90 has an axialextent in the range of about 0.15 to 0.25 and desirably about 0.18 of aninch and in assembly overlies an edge portion 26 of the strip 22 ofcarbon material. The opening 96 of the orifice may have an axial extentin the range of about 1.0 to 1.04, desirably about 1.03 of an inch andin assembly overlies the cavity 50 in the drum 44. Both openings of theorifice may have a circumferential extent in the range of about 0.2 to0.3 and desirably about 0.25 of an inch and may be axially separated byabout 0.12 of an inch. As shown in FIGS. 15 and 17 liquid lead may besupplied under pressure to both a passage 98 extending generally axiallythrough the shoe 56 and through a tube 106 received in the passage. Thepassage 98 may open onto the orifice outlet openings 94 & 96 through apassage 102 defined by tapered walls around the periphery of theorifice. Desirably the orifice passage 102 has axial end walls 104tapered or inclined at an included angle of about 35 degrees and sidewalls 96 tapered or inclined at an included angle of about 20 degreesrelative to a radius of the arcuate face extending through the orificeas shown in FIG. 15. The passage 98 extends through the shoe and incross section (FIG. 15) has a generally circular portion 108 whichadjacent its upper edge merges into the orifice passage 102 and adjacentits lower edge merges into a kidney or bowl shaped portion 110 extendingbelow the lower edge of the orifice passage 102 and rising to merge intothe lower edge of the orifice passage 102 relative to the direction ofrotation 112 of the drum. As shown in FIGS. 15 and 17, desirably liquidlead is also supplied to the orifice through the tube 100 with aplurality of apertures or holes 112 opening toward the orifice passage102 and a downstream end wall 114 with through holes 116. In use, excessliquid lead not entering the cavity 50 is returned through thedownstream end of the shoe passage 98 to the furnace pot 58 of liquidlead. The apertures or holes 112 through the tube 100 tend to directliquid lead generally radially through the orifice 92 and into thecavity 50 of the rotating drum 44 to facilitate casting of a solid leadribbon 24. Excess liquid lead flowing through the shoe 56 heats it andinsures liquid lead at a desired temperature is supplied to the cavity50.

Ribs 120 and 122 project outwardly from the face 90 of the shoe and inassembly with the drum as shown in FIG. 17 extend into the cavity 50adjacent its axial ends to in use inhibit liquid lead from flowingupstream relative to the direction of rotation 112 of the drum. Shortribs 124 and 126 projecting outwardly from the face 90 of the shoe anddisposed generally axially outward of the orifice 92, in operation ofthe machine 40, tend to also inhibit and reduce the extent of axial flowof liquid lead into the carbon fiber material. In operation of themachine 40, the extent of the axial flow of liquid lead into the carbonfiber strip 22 is also reduced by compression of a proportion this stripbetween the circumferential rib 82 of the drum and the opposed face 90of the shoe. However, the extent of this compression must be limited sothat the carbon fiber material is not torn or unduly stressed bymovement of it by the drum 44 relative to the shoe 56. The extent towhich this compression of the carbon fiber material must be limited toavoid tearing or undue stretching of the carbon fiber material may needto be empirically determined depending on various factors including thethickness and density of the strip 22 of the carbon fiber material, thespeed at which the drum 44 rotates, the width of this rib 82, etc. It isbelieved the carbon fiber material may be compressed to 30% to 50% ofits uncompressed nominal thickness. For a carbon fiber material having anominal thickness of about 0.060 of an inch, a rib 82 with an axialwidth of about 0.06 of an inch and a rotary drum speed of about 80 to100 lineal feet/minute, a compression of the strip to a thickness ofabout 0.020 of an inch has been empirically determined to besatisfactory. If desired small vent holes 128 of about 0.94 of an inchin diameter may be provided through the face 90 of the shoe and upstreamof the orifice 92 relative to the direction of rotation 112 of the drum

The forms of the invention herein disclosed constitute presentlypreferred embodiments and many other forms and embodiments are possible.It is not intended herein to mention all the possible equivalent formsor ramifications of the invention. It is understood that the terms usedherein are merely descriptive, rather than limiting, and that variouschanges may be made without departing from the spirit or scope of theinvention.

1. A machine for casting a composite lead carbon fiber battery electrodecomprising, a rotatable drum having a plurality of spaced apart grippersdisposed around the circumference of the drum and configured to engageat least part of a strip of carbon fiber material and releasably retainit on the drum and at least one mold cavity extending circumferentiallyaround the drum and configured to underlie only a portion of atransverse width of a longitudinally elongate strip of carbon fibermaterial received in part on the drum for casting a lead strip attachedto a portion of the strip of carbon fiber material overlying the moldcavity; a shoe having a curved surface complimentary with an arcuatesegment of the drum and having at least one orifice therein opening at aportion of the curved surface between circumferentially opposed ends ofthe curved surface and onto at least part of the mold cavity andconfigured to supply liquid lead to the mold cavity and at least aportion of the strip of carbon fiber material overlying the mold cavity,and the shoe having an inlet and an outlet communicating with theorifice slot; and a device for supplying liquid lead at asuperatmospheric pressure to the inlet in a quantity in excess of thatrequired to supply a continuous flow of liquid lead through the orificeto progressively fill a portion of the mold cavity and engage and atleast in part penetrate at least part of the carbon fiber stripoverlaying the mold cavity as they rotate past the orifice and so thatexcess liquid lead flows through the outlet.
 2. The machine of claim 1wherein the drum also comprises a rib extending circumferentially aroundthe drum and spaced axially inward of an edge of the strip of carbonfiber material and under the strip of carbon fiber material andconfigured to at least in part limit the axial extent to which liquidlead from the orifice extends generally axially onto the strip of carbonfiber material.
 3. The machine of claim 2 wherein the rib iscircumferentially continuous around the drum.
 4. The machine of claim 1wherein the orifice of the shoe comprises a first portion extendinggenerally axially across at least part of the cavity and a secondportion extending across at least part of an adjacent portion of thestrip of carbon fiber material and spaced from the first portion of theorifice.
 5. The machine of claim 2 wherein the orifice of the shoecomprises a first portion extending generally axially across at leastpart of the cavity and a second portion extending across at least partof an adjacent portion of the strip of carbon fiber material and spacedfrom the first portion of the orifice.
 6. The machine of claim 3 whereinthe orifice of the shoe comprises a first portion extending generallyaxially across at least part of the cavity and a second portionextending across at least part of an adjacent edge portion of the stripof carbon fiber material and spaced from the first portion of theorifice.
 7. The machine of claim 1 wherein the cavity comprises aplurality of circumferentially spaced apart ribs in and disposed aroundthe cavity.
 8. The machine of claim 7 wherein the ribs in the cavityextend generally parallel to the axis of rotation of the drum.
 9. Themachine of claim 1 wherein the shoe also comprises a rib adjacent oneend of the orifice, projecting into the cavity, and extendingcircumferentially upstream of the orifice relative to the direction ofrotation of the drum.
 10. The machine of claim 2 wherein the shoe alsocomprises a rib adjacent one end of the orifice, projecting into thecavity, and extending circumferentially upstream of the orifice relativeto the direction of rotation of the drum.
 11. The machine of claim 4wherein the shoe also comprises a rib adjacent one end of the orifice,projecting into the cavity, and extending circumferentially upstream ofthe orifice relative to the direction of rotation of the drum.
 12. Themachine of claim 1 wherein the shoe also comprises a first rib adjacentone end of the orifice, projecting into the cavity, and extendingcircumferentially upstream of the orifice slot relative to the directionof rotation of the drum and a second rib adjacent the other end of theorifice, projecting into the cavity, and extending circumferentiallyupstream of the orifice relative to the direction of rotation of thedrum.
 13. The machine of claim 1 wherein the orifice comprises anelongate slot.
 14. The machine of claim 1 wherein the shoe alsocomprises at least one rib bearing on the strip of carbon fibermaterial, spaced from the orifice, and spaced axially inward from anadjacent edge of the sheet of fiber material, and compressing the fibermaterial between such rib and the drum.
 15. The machine of claim 2wherein the shoe also comprises at least one rib bearing on the strip ofcarbon fiber material, spaced from the orifice, and spaced axiallyinward from an adjacent edge of the sheet of fiber material, andcompressing the fiber material between such rib and the drum.
 16. Themachine of claim 4 wherein the shoe also comprises at least one ribbearing on the strip of carbon fiber material, spaced from the orifice,and spaced axially inward from an adjacent edge of the sheet of fibermaterial, and compressing the fiber material between such rib and thedrum.
 17. The machine of claim 5 wherein the shoe also comprises atleast one rib bearing on the strip of carbon fiber material, spaced fromthe orifice, and spaced axially inward from an adjacent edge of thesheet of fiber material, and compressing the fiber material between suchrib and the drum.
 18. The machine of claim 7 wherein the shoe alsocomprises at least one rib bearing on the strip of carbon fibermaterial, spaced from the orifice, and spaced axially inward from anadjacent edge of the sheet of fiber material, and compressing the fibermaterial between such rib and the drum.
 19. The machine of claim 9wherein the shoe also comprises at least one rib bearing on the strip ofcarbon fiber material, spaced from the orifice, and spaced axiallyinward from an adjacent edge of the sheet of fiber material, andcompressing the fiber material between such rib and the drum.
 20. Themachine of claim 12 wherein the shoe also comprises at least one ribbearing on the strip of carbon fiber material, spaced from the orifice,and spaced axially inward from an adjacent edge of the sheet of fibermaterial, and compressing the fiber material between such rib and thedrum.
 21. A process of making a composite battery electrode comprising,providing a longitudinally elongate strip of an electrically conductivecarbon fiber material; casting an electrically conductive lead or leadalloy ribbon with a continuous flow of liquid lead or lead alloy alongand attached to a longitudinally elongate portion of the strip of carbonfiber material; and severing the strip of carbon fiber material with theattached ribbon into a plurality of electrodes each with a portion ofthe carbon fiber material with a portion of the ribbon attached thereto.